The origins of postmating reproductive isolation: testing hypotheses in the grasshopper Chorthippus parallelus

Although there are several well-established hypotheses for the origins of postmating isolation during allopatric divergence, there have been very few attempts, to determine their relative importance in nature. We have developed an approach based on knowledge of the differing evolutionary histories of populations within species that allows systematic comparison of the predictions of these hypotheses. In previous work, we have applied this methodology to mating signal variation and premating reproductive isolation between populations of the meadow grasshopper Chorthippus parallelus. Here we review the principles behind our approach and report a study measuring postmating isolation in the same set of populations. The populations have known and differing evolutionary histories and relationships resulting from the colonization of northern Europe following the last glaciation. We use a maximum-likelihood analysis to compare the observed pattern of postmating isolation with the predictions of the hypotheses that isolation primarily evolves either as a result of gradual accumulation of mutations in allopatry, or through processes associated with colonization, such as founder events., We also quantify the extent to which degree of postmating isolation can be predicted by genetic distance. Our results suggest that although there is only a weak correlation between genetic distance and postmating isolation, long periods of allopatry do lead to postmating isolation. In contrast to the pattern of premating isolation described in our previous study, colonization does not seem to be associated with increased postmating isolation

Dynamic mimicry in an Indo-Malayan octopus

During research dives in Indonesia (Sulawesi and Bali), we filmed a distinctive long-armed octopus, which is new to science. Diving over 24 h periods revealed that the 'mimic octopus' emerges during daylight hours to forage on sand substrates in full view of pelagic fish predators. We observed nine individuals of this species displaying a repertoire of postures and body patterns, several of which are clearly impersonations of venomous animals co-occurring in this habitat. This 'dynamic mimicry' avoids the genetic constraints that may limit the diversity of genetically polymorphic mimics but has the same effect of decreasing the frequency with which predators encounter particular mimics. Additionally, our observations suggest that the octopus makes decisions about the most appropriate form of mimicry to use, allowing it to enhance further the benefits of mimicking toxic models by employing mimicry according to the nature of perceived threats

Sympatric speciation in an age-structured population living on a lattice

A square lattice is introduced into the Penna model for biological aging in order to study the evolution of diploid sexual populations under certain conditions when one single locus in the individual's genome is considered as identifier of species. The simulation results show, after several generations, the flourishing and coexistence of two separate species in the same environment, i.e., one original species splits up into two on the same territory (sympatric speciation). As well, the mortalities obtained are in a good agreement with the Gompertz law of exponential increase of mortality with age.Comment: 5 pages including 3 encapsulated postscript (*.eps) figures; To appear in European Physical Journal

Superior sperm competitors sire higher-quality young

The evolution of polyandry remains controversial. This is because, unlike males, in many cases multiple mating by females does not increase fecundity and inevitably involves some costs. As a result, a large number of indirect benefit models have been proposed to explain polyandry. One of these, the good sperm hypothesis, posits that high-quality males are better sperm competitors and sire higher-quality offspring. Hence, by mating multiply, females produce offspring of superior quality. Despite being potentially widely applicable across species, this idea has received little attention. In a laboratory experiment with yellow dung flies ( Scathophaga stercoraria ) we found that males that were more successful in sperm competition also had offspring that developed faster. There was no relationship between paternal success in sperm competition and the ability of offspring to survive post-emergence starvation. Since faster development times are likely to be advantageous in this species, our data provide some support for polyandry evolving as a means of producing higher-quality offspring via sperm competition

Some characteristics of early Australian PhD theses

The first PhDs in Australia were awarded in the late 1940s and 1950s. This paper reports on some research being conducted by the authors that involves reviewing early PhD theses from the Universities of Melbourne, Queensland and Sydney. The paper discusses some selected features of the candidates, fields of study and theses. Photographs and facsimiles from a selection of early theses illustrate some peculiarities of the time.<br /

Female impersonation as an alternative reproductive strategy in giant cuttlefish

Out of all the animals, cephalopods possess an unrivalled ability to change their shape and body patterns. Our observations of giant cuttlefish (Sepia apama) suggest this ability has allowed them to evolve alternative mating strategies in which males can switch between the appearance of a female and that of a male in order to foil the guarding attempts of larger males. At a mass breeding aggregation in South Australia, we repeatedly observed single small males accompanying mating pairs. While doing so, the small male assumed the body shape and patterns of a female. Such males were never attacked by the larger mate-guarding male. On more than 20 occasions, when the larger male was distracted by another male intruder, these small males, previously indistinguishable from a female, were observed to change body pattern and behaviour to that of a male in mating display. These small males then attempted to mate with the female, often with success. This potential for dynamic sexual mimicry may have played a part in driving the evolution of the remarkable powers of colour and shape transformation which characterize the cephalopods

The regulation of non-local tertiary courses in Hong Kong

This paper reports on some research from an ARC project conducted by the authors into the ways in which Australian universities establish colaborations with partners in Hong Kong and Papua New Guinea to offer courses in those countries. One feature of such collaborations in Hong Kong is the way in which, since 1997, the local Special Administrative region government regulates the provision on \u27non-local courses\u27 by mean of an ordinance. The paper describes and analyses the impact of the ordinance on both local and overseas stakeholders. This impact represents a particular enactment of matters of globalisation and localisation in education. The paper reports on the issues, which have emerged which, are leading to current moves to modify the ordinance\u27s provisions.</div

Quality of life and building design in residential and nursing homes for older people

Older people living in residential and nursing care homes spend a large proportion of their time within the boundaries of the home, and may depend on the environment to compensate for their physical or cognitive frailties. Regulations and guidelines on the design of care buildings have accumulated over time with little knowledge of their impact on the quality of life of building users. The Design in Caring Environments Study (DICE) collected cross-sectional data on building design and quality of life in 38 care homes in and near Sheffield, Yorkshire. Quality of life was assessed using methods which included all residents regardless of their frailty, and staff morale was also assessed. The physical environment was measured on 11 user-related domains using a new tool, the Sheffield Care Environment Assessment Matrix (SCEAM). Significant positive associations were found between several aspects of the built environment and the residents' quality of life. There was evidence that a focus on safety and health requirements could be creating risk-averse environments which act against quality of life, particularly for the least frail residents. Staff morale was associated with attributes of a non-institutional environment for residents rather than with the facilities provided for the staff. The new tool for assessing building design has potential applications in further research and for care providers